The survey released on Tuesday shows Malaysia’s ruling Barisan Nasional (BN) coalition would win 37.3 percent of the popular vote in peninsular Malaysia, down from 40.3 percent the firm had predicted last week.

The opposition alliance’s support fell to 43.4 percent, it showed.

Najib’s coalition will win 100 of the 222 seats in parliament, with contests in 37 constituencies too close to call, the survey showed, while the opposition alliance will win 83 seats.

Barisan Nasional won 133 seats in the 2013 polls.

In Wednesday’s vote, Najib goes up against his former mentor turned critic Mahathir Mohamad, once a long-serving prime minister who now leads the opposition.

(This version of the story corrects paragraph three to show support for opposition alliance fell, not rose).